The present invention relates generally to eddy current inspection, and more particularly to components having permanently affixed eddy current elements.
Eddy current inspection is commonly used to detect flaws in electrically conductive components such as aluminum aircraft fuel tanks. Electromagnetic induction is used in this type of inspection to induce eddy currents in the component being inspected. Generally, a probe having one or more coils is used to generate alternating magnetic fields which induce the eddy currents in the component. When flaws are present in the component, the flow of eddy currents is altered. The altered eddy currents produce changes in a secondary magnetic field which are detected by the probe. The probe generates an electrical signal in response to the altered secondary magnetic field. The amplitude and phase of the electrical signal is generally proportionate to the size of the flaw.
As previously mentioned, a probe having one or more coils was used in the past to perform the inspections. The probe was positioned adjacent to the surface being inspected. Using a probe to inspect interior surfaces of components such as bulkheads forming fuel tanks inside aircraft wings required disassembly of the structure to position the probe adjacent the surface. Depending upon the complexity of the structure, disassembly, inspection and reassembly can take several hours, days, weeks or longer. During this time, the structure is unavailable. Further, the cost of labor required to perform these tasks can be high. Accordingly, a need exists for a method and apparatus for performing eddy current inspection of interior surfaces of complex structures without disassembling the structures.
Among the several features of the present invention may be noted the provision of a method of inspecting a preselected area of an electrically conductive component to determine whether flaws are present therein. The method comprises the steps of permanently mounting an eddy current element on the component over the preselected area and energizing the element to generate alternating magnetic fields proximate the component thereby inducing eddy currents in the component. An electrical signal generated by a secondary magnetic field formed proximate the component by the eddy currents is detected by the element, and the detected electrical signal is compared to a reference signal to determine whether the detected signal is different than the reference signal. A difference indicates a flaw is present in the component.
In another aspect, a method of the present invention for installing inspection apparatus on a component comprises permanently mounting an eddy current element on the component and attaching a conduit to the component. A lead is attached to the eddy current element and threaded through the conduit for selectively connecting the eddy current element to remote eddy current inspection equipment.
In still another aspect, the present invention includes inspection apparatus for detecting flaws in a preselected area of an electrically conductive component. The apparatus includes a substrate sized and shaped for covering the preselected area of the component. The substrate includes an adhesive for attaching the substrate to the component over the preselected area. Further, the apparatus includes a primary eddy current element mounted on the substrate sized and shaped for covering at least a portion of the preselected area to detect flaws in the component.
Yet another aspect of the present invention includes an electrically conductive component having an area selected for inspection in combination with apparatus for detecting flaws in the selected area of the component. The apparatus comprises a substrate mounted on the component over the area selected for inspection and a primary eddy current element mounted on the substrate over at least a portion of the selected area for detecting flaws in the area.
Other features of the present invention will be in part apparent and in part pointed out hereinafter.